X-ray apparatus



Jan. 28, 41941. A. BoUwERs `ET A1. 2,230,176

`X-RAY APPARATUS Y Filed Feb. 8, 1959 6a 5r 5*# .fa sa sa sa 5.a

ATTO/UVEK Patented Jan. 28, 1941 I UNITED STATES PATENT OFFICE X-RAY APPARATUS Albert Bouwers and Adrianus Verhoeff, Eindhoven, Netherlands, assignors, by mesne assignments, to Hartford National Bank and Trust Company, Hartford, Conn., as trustee Application February 8, 1939, Serial No. 255,330 In Germany February 25, 1938 9 Claims. (Cl. Z50-87) Our invention relates to X-ray apparatus in transformer in a common envelope rapidly inwhich a high-tension supply transformer and an creases according to the voltage, i. e. in case of X-ray tube form a structural unit, and more voltages in excess of 100 kv. it increases more particularly to apparatus for operation on high than proportionally to the Voltage. This increase 5.5 voltages, for instance above D kv. in weight is due mostly to the high-tension trans- 5 With lower Voltage, for instance below about former, and by using a Greinacher cir-cuit, as

100 kv., there are n-o particular di'iculties in hereinafter described, a transformer for half of keeping the weight of such apparatus Within the voltage suffices and the weight of the transpractical limits. However, with higher working former is thus reduced by more than one-half.

voltages the dimensions of the apparatus are The X-ray tube also plays its part in the re- 10 increased With the result that the tube and duction of weight. In fact, if the tube is fed transformer are usually arranged separately and with direct voltage, the size of the tube, as is lWell high tension is supplied to the X-ray tube by known, may be materially smaller than in case flexible cables. For deep-therapy installations, of feeding with alternating voltage, and this re- 1"'5 for example, the structural unit of X-ray tube sults in a reduction of the dimensions of the 15 and transformer assumes a large Weight, and as apparatus. Also the security of service of the such units are not readily movable, it is necessary apparatus is increased by feeding with rectified to provide special supporting means which are voltage. complicated, expensive and bulky. The use of a voltage-multiplying circuit ar- The main object of our invention is to elimirangement requires not only the addition of con- 20 nate the above drawbacks and produce a compact vdensers and rectifying tubes, but also of heating X-ray apparatus which is light in Weight and transformers. Apparatus for small powers havreadily supported. For this purpose We enclose ing an X-ray tube fed directly from a high-tenthe high-tension supply source in a metal ension transformer and in which a control of the velope which forms a constructional unit with current is not required, can be supplied without the X-ray tube, and for the source use a higha heating transformer. In that case the heating tension transformer and a voltage-multiplying current may be derived from part of the secondcircuit arrangement. ary Winding of the high-tension transformer.

The idea of reducing the weight of an X-ray However, when it is necessary to control the heaty apparatus by the addition of a plurality of coning current, a heating transformer must be em- 30 structional parts determined by the Voltage-mulployed in the apparatus if the incandescible cathtiplying lcircuit arrangement, such as condensers ode is not grounded. and rectifying tubes, might appear odd, but it is If a high-tension transformer is used in connot easily effected Without further means. It has junction with a Greinacher circuit arrangement,

351 previously been proposed, by locating transforman additional heating transformer must be added ers, condensers, rectifier valves and an X-ray for supplying heating current to the incandescitube together in a common grounded envelope, ble cathode of the rectifying tube which is not to house the X-ray installation within the treatconnected to the .high-tension transformer. If ment room, but such constructions have not made voltage control is not desired, the heating vcurrent it possible to provide an apparatus having such of the second rectifier may be taken from the low Weight that it could be suspended as a unit high-tension Winding of the transformer. In inamovable manner. most cases, however, the high tension must be The invention is based on the recognition of the adjustable and in such cases a separate heating fact that the voltage-multiplying circuit arrangetransformer is required also for the second tube,

4'51 ment permits the obtainance of a substantial because the heating current of the rectifier tube 45 saving in weight provided that a further condican not be varied by controlling the high tension. tion, which will be explained hereinafter, be When a plurality of condenser-valve groups is fulfilled. used it is necessary to use an additional heating An apparatus according to the invention for a transformer for each additional rectifier tube.

' Working voltage of 200 kv..has, `for example, only These transformers have such a high weight that 50 about half of the weight of an apparatus conthey would render illusive the reduction in Weight stituted by a transformer and an X-ray tube di- Withv respect to apparatus having a tube -directly rectly connected thereto. This is due to the fact fed `from the transformer. that theweight of an apparatus consisting suby vAccording to the invention this reduction in stantially of an `X-ray tube and a high-tension Weight of the high-tension transformer may be 55 obtained by using a voltage-multiplying circuit arrangement in such manner that at least those cathodes of high-tension rectiiiers which have a high potential difference with respect to ground and are not connected to the transformer, are energized with high-frequency current from a highfrequency generator arranged separately from the apparatus. The energy may be transmitted from the high-frequency generator to the incandescible cathode by means of heating transformers, and for high-frequency current, such transformers for a given power, have a much lower weight than for low-frequency current. Consequently it is advantageous yfor X-ray apparatus comprising a constructicnally united tube and source of high tension to use a voltage-multiplying circuit arrangement.

The feeding of the high-tension circuit may also be eiected with high-frequency alternating current. This requires -a generator for a power of another order of magnitude (say 1 kw). This method of operation will be advantageous only with installations for higher voltages, for example above 300 kv.

Heating transformers for they incandescible -cathodes which are directly connected to a hightension condenser can be avoided in an apparatus according to the invention by passing the high-frequency filament current to the incandescible cathodes through the high-tension condensers of the voltage-multiplying circuit arrangement. In this case the economies in weight are still materially increased.

If the apparatus is provided with a Greinacher circuit arrangement having grounded condenser units, the arrangement is simplified when each of the condenser units comprises two condensers connected in parallel with respect to the current of the tube. These condensers are interconnected on their high-tension side by the adjacent incandescible cathode, and ea-ch of them is connected on the low-tension side to a terminal of the high-frequency generator so as to 'be seriesconnected with respect to the filament current.

In order that our invention may be clearly understood and readily carried into eiect, we shall describe the same in more detail with reference to the accompanying drawing, in which Figure 1 is a partly-sectionized side View of an X-ray apparatus according to the invention, and

Fig. 2 is a schematic wiring diagram of the apparatus illustrated in Fig. 1.

The apparatus illustrated in Fig. 1 com-prises a metal housing having a portion A housing the voltage supply apparatus, and a portion B housing an X-ray tube. The` portion A comprises two elongated cup-shapedI metal members 28 and' 29 which have flared endsy secured together to form an enlarged central space 30, and have hollow extensions 44 and 45 respectively forming flanges 40 and 41. Member 29 has an open end provided with a removable cover 21. The apparatus is rotatably supported from an arm 69 of an adjustable stand (not shown), and for this purpose we use ayoke 59 rotatably mounted on arm 69 and having two extensions 6d and 6I which are provided with annular grooves cooperating in a slidable manner with ringsy mounted on portions 28 and 29.

Within the central space 38 is a high-tension transformer 32 of the shell type having a core 3 I a low-'tension primary winding 8 and a hightension secondary winding 9. suitably supported from member 29 are a condenser unit 3 comprising two high-tension condensers 38 and 39,V

and a high-tension rectifier tube 33 having an incandescible cathode I4 )and an anode I5. Tube 33 is preferably of the ion rectifying type and is subdivided as regards voltage by a Iplurality of metal rings 34 and annular condensers 35, so that the tube can have a small weight and size. The cathode I4 is preferably of the activated type, as this reduces the heating current required. Tubes of this type are described in more detail in the U. S. Patent 2,020,077 to Mulder et a1.

ina similar manner a condenser unit 2 comprising two high-tension condensers 4 Iy and 42, a high-tension rectifier tube 36 having an incandescible cathode II andan anode I2, and condensers 31 for the subdivision of voltage across tube 35, are supported in the portion 28. Tube 35 and condensers 31 are similar to tube 33 and condensers 35 respectively.

An annular ltrans-former 58 surrounds the end of tube 33 and serves to heat cathode I4 in a manner later to be described.

Portion B comprises a central cylindrical portion 50 and two apertured end portions 48 and 40 secured in a removable manner to the flanges 46 and' 41 respectively. Supported within the central part 50 of por-tionB is an X-ray tube having an envelope comprising a central cylindrical metal member 52, to the ends of which are hermetically fused two yglass re-entrant por-k tions 53, only one being shown. Supported from the re-entrant portions are an anode 51, and a cathode structure 5E comprising an incandescible cathode I8. Member 52 is electrically connected thro-ugh a metal ring 83 to the portion B which is grounded during operation. Member 52 is provided with a Window 53 for the exit of the X-rays, and a ring 64 of lead provided with an aperture t5, which ring surrounds the central portion of the tube to absorb undesirable X-rays. A member 54 of insulating material, for instance a molded member of Bakelite, covers the outer surface of re-entrant portion 53 and extends slightly over the metal member 52 preferably with the interposition of a suitable insulating cement to avoid the occurrence of air spaces. Tubes `of Ithe a'bove type have been described in detail in the U. S. Patent 2,110,259 to Albert Bouwers.

The cathode I8 and anode 51 are connected to the voltage supply apparatus contained in housing A, and the connections, which will be indicated in connectionl with Fig. 2, are made with the aid of suitable insulating members and contacts. More particularly, the terminals of cathode I8 are connected to the two contacts of a two-pole receptacle carried by member 54, which contacts cooperate with a two-pole plug 62 supported by a member 55 of insulating material. The two poles of plug 62 are connected through conductors 8G and BI, which pass through member 55 to two contacts of aV second two-pole' plug 40 mounted on the end member 5.5'. Plug 40 cooperates with-the two contacts of a receptacle mounted on condensers 35. Theselatter contacts are connected in a manner to be described;v one to anode I5 and one terminal of condenser 38, and the other to one terminal of condenser 39. In a similar manner, and with the aid of a single-pole plug 43, anode 51 is connected to one terminal of condenser v42 and Vto one end of cathode II. With .such type .of connections, and with a removable mechanical connection at flanges 46 and 41, the X-ray tube may be readily replaced.

The electrical connections of the apparatus illustrated in Figure 1 are shown schematically in Figure 2 in which the same parts are indica-ted by the reference numerals used in Figure 1.

As shown in Figure 2, a Greinacher circuit arrangement is employed, and for this purpose the two condenser units 2 and 3 are charged by rectied alternating current. The alternating current at a voltage of about 100 kv. is supplied from the high--tension secondary Winding 9 of transformer 32 whose primary Winding 8 is provided with leads 88 and 89 Which pass through the metal housing A in an insulating manner and are connected to a suitable supply of low-tension current supply. The rectier tube 36 is located in the charging current circuit of condenser unit 2, and condenser unit 3 is charged by the antiphase of the alternating current through the rectifying tube 33.

Condenser 42 has one terminal connected to the grounded housing 28 and its other terminal connected to one end of cathode II and to the anode 51 of the X-ray tube I. The other end of cathode II is connected to one terminal of condenser 4I whose other terminal is connected to a conductor 61 passing through the housing 28 and insulated therefrom. Condenser 39 has one terminal connected to the grounded housing 29 at a point 85 and its other terminal connected through conductor 8I to one end of cathode I8 Whose other end is connected through conductor 80 to point 81. Point 81 is connected to anode I5 andpto one terminal of condenser 38 whose other terminal is connected to a conducto-r 56 which passes through housing 29 and is insulated therefrom.

As a result of the above connection, the voltages applied across X-ray tube I is the sum of the voltages of the condenser units 2 and 3, and thus is twice the voltage produced by the hightension Winding 9.

The secondary winding 9 has one terminal connected to the core 3| and to the grounded housing 28, and has its other terminal connected to anode I2 and to one end of cathode I4. The

4secondary winding of transformer 58 is connected across cathode I4, Whereas itsv primary winding has one end connected through a conductor 61 to one terminal o-f condenser 4I and to y a conductor 68 which passes through housing 60 length, for example, of 300 meters.

" 29 and is insulated therefrom for low voltage.

The other end of the primary ywinding is connected to the grounded' housing 28 to which the core vof transformer 58 is also connected.

The conductors 86 and 68 are connected to the L terminals I9 and 20 respectively of a high-frequency generator 2|, and conducto-r 68 is connected through a regulating resistance 22 to terminal 28. The generator may be a tube transmitter, for say 100 Watts having a wave- A current ilows from the high-frequency generator n 2I through the condensers 4I and 42 to the incandescible cathode II so that cathode IIr attains its emissive temperature'. Furthermore, a high-frequency current flo-ws through regulating resistance 22 and the condensers 38 and 39 to the cathode I8, to thereby heat the cathode to its emissive temperature. v

From the above it is seen that condensers 4I and 42 and condensers 38 and 39 respectively are connected in series with the high-frequency heating current. More particularly, the heating circuit comprises two parallel branches. One branch can be traced from terminal 28, conductor 61, condenser 4I, cathode II, condenser 42, and back through ground to terminal I9. The second branch can be traced from terminal 20, resistance 22, conductor 66, condenser 38, conductor 80, cathode I8, conductor 8l, condenser 39, and back through ground to terminal I9.

It should be noted that the high-tension sides of the condenser units 2 and 3 are connected to the anode 51 and cathode I8 respectively of the X-ray tube. Furthermore, the high-tension sides of condensers 4I and 42 are connected to cathode II, and the high-tension sides of condensers 38 and 39 are connected-to the cathode I8. The low-tension sides of condensers 4I-42 and 38-39 respectively are connected to terminals I9 and 28 of the generator 2 I.

The voltage drop produced across condenser units 2 and 3 by the passage of the high-frequency current is practically negligible with respect to the high-tension of winding 9 because of the high frequency of the alternating current. For example, if each of the condensers 38, 39, 4I and 42 have a capacity of 0.5 microfarad and the high-frequency current has a frequency of about 106 cycles per sec., the wattless voltage drop will be only about 3 volts when the heating current is l amps., which has practically no effect on the voltage across the X-ray tube.

'Ihe heating transformer 58 serves to heat cathode I4 and for this purpose its primary winding has one end grounded and its other end connected to conductor 61, i. e., connected to the terminals I9 and 20 of the generator 2|. This transformer requires only a very small iron core because it is used on high-frequency current. On

the other hand, its windings must be insulated toI withstand the full voltage of winding 9. Thus by using the high tension condensers 4I, 42, 38 and 39 as supply conductors for the heating current of cathodes II and I2, two of these transformers are eliminated, which considerably reduces the size, weight, and cost of the apparatus.

The advantages of the invention are particularly marked when higher voltages are concerned. More particularly, for a voltage of 300 kv., the combination of transformer and X-ray tube of the prior art, weighs several hundred kgs. With this heavy weight the constructional union of X- ray tube and transformer is almost out of question for movable apparatus. However, an apparatus according to the invention comprising a transformer for 100 kv. and a corresponding voltage-multiplying circuit arrangement for a total voltage of 300 kv. weighs less than 100 kg.

For example, the apparatus illustrated in the drawing may have a weight less than 100 kgs., which makes it very suitable for therapy installations, is readily movable, and can be readily supported to the arm 89 which is adjustable in height, and if desired is also rotatable. In prior apparatus with D. C. feeding of the X-ray tube from a transformer for voltages in excess of 200 kv., an impracticable conveying device would be required, and adjustment in height had to be effected by raising or lowering the irradiation table. With the construction of the present invention the complete apparatus can be suspended in the same manner in which only the X-ray tube is usually suspended, and as a result the hightension cables, which hindered the operation of .previous apparatus, are eliminated. V

While we have described our invention in connection with specific examples, we do not wish to be limited to the exact details of constructions illustrated and described, because obvious modifications will occur to a person skilled in the art.

What we claim is:

1. An X-ray apparatus comprising a housing having a metal surface adapted to be grounded during operation of the apparatus, an X-ray tube secured to said housing to form a structural unit therewith and having an incandescible cathode, means for supplying operating current vto said X-ray tube comprising a high-tension transformer Within said housing and voltagemultiplying means Within said housing and including a plurality of high-tension discharge tubes having incandescible cathodes, the cathode of one of said discharge tubes being at a highpotential With respect to ground and being electrically separated from the transformer, and means for heating said latter cathode with highfrequency current including a high-frequency generator located outside the housing.

2. An X-ray apparatus comprising a housing having a metal surface adapted to be grounded during operation of the apparatus, an X-ray tube secured to said housing to form a structural unit and having an incandescible cathode, means for supplying operating current to said X-ray tube comprising a high-tension transformer and voltage-multiplying means within said housing, said voltage-multiplying means including a plurality of high-tension condensers and high-tension discharge tubes having incandescible cathodes, the cathode of one of said discharge tubes being at a high-potential with respect to ground and being electrically separated from the transformer, and means for heating said latter cathode with highfrequency including a generator located outside the housing and a heating circuit including one of said condensers.

3. An X-ray apparatus comprising a meta housing adapted to be grounded during operation of the apparatus, an X-ray tube including an incand-escible cathode, said tube being secured to said housing to form a structural unit therewith, means for supplying operating current to said X-ray tube comprising a voltage-multiplying circuit arrangement including a high-tension transformer, a plurality of condenser units each having two condensers, and a plurality of hightension discharge tubes having incandescible cathodes, the cathode of one of said discharge tubes being at a high potential with respect to ground and being electricallyseparated from the transformer, and means for heating said latter cathode with high-frequency current including a high-frequency generator located outside thehousing, said means comprising a heating circuit having a plurality of parallel-connected branches each including one of the cathodes and the two condensers of one of the condenser units connected in series.

4. An X-ray apparatus comprising a metal housing adapted to be grounded during operation of the apparatus, an X-ray tube secured to said housing to form a structural unit and having an incandescible cathode, means for supplying operating current to said X-ray tube comprising a high-tension transformer, and a Voltage-multiplying arrangement Within said housing and including a plurality of high-tension ion rectier tubes having incandescible cathodes, the cathode of one of said discharge tubes being at a high potential with respect to ground and being electrically separated from the transformer, means to subdivide the voltage across said rectifier tubes including metal members and annular condensers surrounding the tube, and means for heating said latter cathode with high-frequency current including a generator located outside the housy ing. i k

5. An X-ray apparatus comprising a metal housing adapted to be grounded during operation of the apparatus and comprising two portions secured together to form a structural unit, an X-ray tube in .one of said portions and having an incandescible cathode, means for supplying operating current to said X-ray tube comprising a high-tension transformer, and a voltage-multiplying arrangement within the second portion and including a plurality of high-tension discharge tubes having incandescible cathodes, the cathode of one of said discharge tubes being at a high potential with respect to ground and being electrically separated from the transformer, and means for heating said latter cathode with high-frequency current including a high-frequency generator located outside the housing. y

6. An X-ray apparatus comprising an elon-' gated metal housing adapted to be grounded during operation of the apparatus and having two extending portions, an X-ray tube supported from said extending portions, means for supplying operating current to said X-ray tube comprising a high-tension transformer arranged in the central part of the housing, and a voltagemultiplying arrangement including a plurality of high-tension condensers and discharge tubes having incandescible cathodes, said condensers and discharge tubes being arranged at the sides of the transformer, the cathode of one of said discharge tubes being at a high potential with respect to ground and being electrically separated from the transformer, and means forfheating said latter cathode with high-frequency current including a generator located outside the housing.

'7. An X-ray apparatus comprising a metal housing adapted to be grounded during operation of the apparatus and having projecting portions, an X-ray tube supported from said projecting portions to form a structural unit, means for producing operating current for said X-ray tube comprising a high-tension transformer, and a voltage-multiplying arrangement within said housing and including a plurality of high-tension discharge tubes having incandescible cathodes, the cathodes of one of said discharge tubes being at a high potential with respect to ground and being electrically separated from the transformer, means for heating said latter cathode with high-frequency current including a highfrequency generator located outside the housing, and means for conducting the current to the X-ray tube including insulating members secured to the X-ray tube and contact plugs supported by said members.

8. An X-ray apparatus comprising a metal housing adapted to be grounded during operation of the apparatus, said housing comprising two elongated hollow members secured together and each having a projecting portion, an X-ray tube supported from said projecting portions to form a structural unit, means for supplying operating current to said X-ray tube, comprisingV a high-tension transformer in the central part of the housing, and a voltage-multiplying arrangement including a plurality of high-tension condensers and high-tension discharge tubes having l incandescib-le cathodes, said condensers and discharge tubes being arranged within said housing and to the sides of lsaid transformer, the cathode of one of said discharge tubes being at a high potential with respect to ground and being electrically separated from the transformer, and means for heating said latter cathode with high-frequency current including a generator located outside the housing.

9. An X-ray apparatus comprising a metal housing comprising two elongated hollow members each having a tubular projection and flared ends, said hollow members being secured together at their flared ends, and a tubular member secured to said projections, an X-ray tube within said tubular member and having an incandescible cathode, means to produce operating current for said X-ray tube including a hightension transformer within the space formed at the junction of said flared ends, and voltagemultiplying means including high-tension condensers and high-tension rectiers having incandescible cathodes, said condensers and rectiiers being disposed within said hollow members to the sides of the transformer, the cathode of one of said discharge tubes being at a high potential With respect to ground and being electricallyseparated from said transformer, means connecting said X-ray tube to said current-producing means and extending through said tubular projections, and means for heating said latter cathode with high-frequency current including a generator located outside the housing. 

